This invention relates to a belt, for example, a power transmission belt such as a V-ribbed belt or a transfer belt such as a flat belt, used in a manner that a part of the belt surfaces is brought into contact with pulleys, and particularly relates to improvements in the placement of a mark provided on a surface of the belt for indicating the history of belt manufacturing.
Conventionally, in order to drive auxiliaries or the like, of an automobile engine, there is known a technique that a rotational force of a crank shaft of the engine is transmitted to each of the auxiliaries through a V-ribbed belt as shown in FIG. 7. The V-ribbed belt is so composed that a plurality of ribs a, a, . . . extending along the length of the belt are formed in parallel with each other in a belt widthwise direction on the bottom face of the belt as an inner periphery of the belt (lower face side of the figure). In other words, the V-ribbed belt wound around a plurality of pulleys brings the bottom face thereof into contact with each of the pulleys so that power transmission is accomplished by friction between the belt and each pulley.
On the back face of the above-mentioned V-ribbed belt (upper face side of the figure), there is provided a mark b indicating the history of belt manufacturing such as a manufacturer and a lot number when the belt was manufactured. For the formation of such a mark b, there is a typical method of using a transfer mark material formed such that a mark layer is provided on one surface of a base material. In detail, the transfer mark material is put on the belt back face so as to bring the mark layer into contact with the belt back face, and is heated while pressure is applied to the transfer mark material and the belt from the base material side so that the mark layer is transferred to the belt back face. Then, only the base material is removed from the belt back face.
Meanwhile, for the purpose of increasing the winding angle of the belt around the pulley for heavy duty power transmission and for the purpose of multi-pulley driving, a layout such that the belt back face as well as the belt inner periphery are brought into contact with the pulleys and a layout that power transmission is made also between the belt back face and the pulley have been increasingly adopted.
In such layouts, the above-mentioned V-ribbed belt has a problem wherein inconveniences such as abnormal noise and rubber adhesion during the belt running easily occur at that part of the belt back face on which the mark b is formed.
Thus, the mark b wears away by contact or friction with the pulleys and readily becomes unrecognizable at an early stage. If a long time passes under such a condition, it becomes difficult to track the history of belt manufacturing from the mark b.